Distillation



March 10, 1964 B. s. FRIEDMAN 3,124,524

METHOD OF PRODUCING A HIGH OCTANE GASOLINE BY REFORMING A NAPHTHA IN TWOSTAGES Filed June 1, 1959 26 STORAGE 32 TANK 24 J 1 HEATER 3o 29 gEXTRACTOR REACTOR REACTOR DISTILLATION 35 COLUMN 36 9 STORAGE TANKHEATER a? DISTILLATION 38 lo COLUMN 4| 42 u REACTOR 4lo 2 '4 is\ ,40 .3REACTOR 47 sfs SEPARATOR 44 48 I8 T l5 SEPARATOR L I 2o DISTILLATION 4346 f COLUMN SEPARATOR i zz DISTILLATION COLUMN 23 I 5o l FRACTIONATORINVENTOR BERNARD S. FRIEDMAN ATTORNEY United States Patent 1 3,124,524METHQI) 0F IRQDUCING A HIGH OCTANE GASDLINE BY REFGRMENG A NAIHTHA INTWO STAGES Bernard S. Friedman, Chicago, lib, assignor, by mesneassignments, to Sinclair Research, Inc, New York,

N.Y., a corporation of Delaware Filed June 1, N59, Ser. No. 817,963-

4 Claims. (Cl. 298-65) 7 This application is a continuation-in-part ofapplication Serial No. 628,666, filed December 17, 1956, now abandoned,and relates to a method for the conversion of hydrocarbon fractionsboiling in the motor fuel range to obtain products of higher octanevalue. More specifically, my invention is directed to a multi-stageprocedure involving the use of a plurality of different catalysts totransformthe constituents of straightrun naphthas to higheroctanecomponents.

In recent years the automobile manufacturers have steadily increased thecompression ratios of their spark ignition engines as a means ofobtaining more power and greater efliciency. As the compression ratiosof the engines increase, the hydrocarbon fuel employed must be of higheroctane value to provide efiicient knock-free o eration notwithstandingthat fuel octane can be increased through the addition of tetraethyllead; and other undesirable aspects of engine operation, for instancepreignition, can be overcome by the use of other additive components.Thus the problem remains for petroleum refiners to produce higher octanebase hydrocarbon fuels under economically feasible conditions.

These refiners now have installed a substantial number of units forreforming straight run petroleum fractions in the presence of freehydrogen and over a platinum met-al alumina catalyst to obtainrelatively high octane products. Primarily these products, frequentlycalled reformates, are blended with other gasoline components such asthermal and catalytically cracked gasolines, alkylate, etc., andadditives such as tetraethyl lead in obtaining present-day motor fuels.The reforming operation has a number of disadvantages. First, as theoctane requirements of the blended engine fuels rise, the octane qualityof the reformate must also increase if the blends be otherwiseunaltered. increase results in a substantial reduction in yieldparticularly when obtaining reform-ates having octanes (RON neat) of theorder of 90 to 95 or above. As the severity of the operation isincreased, the platinum metal containing catalyst becomes fouled moreoften with carbonaceous deposits which requires more frequentregeneratio-ns and/or replacements. As the platinum metal-aluminacatalysts are relatively expensive, either replacement or withdrawalfrom use during regeneration materially increases the cost of providinga given volume of reformate. These and other factors affecting theyield-octane number-cost relationship make it desirable for the refinerto consider various ways in which high octane hydrocarbon fuelcomponents can be obtained by employing processing methods other than orin conjunction with the platinum metal-alumina catalyst reformingoperation.

One method now under consideration by petroleum refiners for obtainingstocks of higher octane value involves the isomertization of parafiinichydrocarbons boiling in the motor fuel range. In general, as the sidechain branching of normal parafiins and of slightly branchedisoparalfins increases, their octane ratings rise. A number of catalystsare known as being useful in this type of operation and such catalystsinclude hydrogen fluoride-boron trifluoride (see US. Patents Nos.2,513,103 and 2,446,- 998) and platinumalumina.

In the present invention I have devised a multistage procedure involvingthe use of a plurality of dif erent catalysts to transform theconstituents of straight run 3,124,524 Patented Mar. 10, 1964 naphthasto higher octane components. In the first reaction stage of my systemthe straight run naphtha is reformed over a platinum group metahaluminacatalyst and a selected, low octane C -C fraction of the reformate isthen treated with a hydrogen fluoride-boron trifluoride catalyst underparticular conditions to give a further increase in octane rating.

Particularly, by operating my second stage reaction system under givenprocessing conditions I have obtained material advantages in terms of anincrease in the yieldoctane relationship of the gasoline boiling rangehydrocarbons. Although my second stage system effects isomerizationreactions, there is also considerable evidence at this time that otherreactions such as disproportionation, polymerization and alkylation takeplace. By employing my improved process the operator can supplyisoparafi'lns for various uses and particularly as the yield-octanerelat-ionship of the gasoline boiling range product is exceptional mymethod affords an advantageous means for obtaining higher octanegasoline blending components which permit a petroleum refiner to elevatethe octane rating of his gasoline pool.

The advantageous yield-octane relationships afforded by my method aredue among other things to the charging to the hydrogen fluoride-borontrifiuoride reaction system of substantial amounts of isobutane. Thus Iprovide at least about 5 0% by Weight of isobutane based upon the chargeof parafiinic feedstock boiling in the motor fuel range. The upper limiton the amount of isobutane charged is primarily an economic questioninvolving factors such as the cost of distilling C s from the liquidproduct, the value of the liquid product, and the cost of increasedconsumption of butanes. However, in general there does not seem to beany advantage in employing more than about 600 Weight percent of theisobutane and preferably I charge about to 300%.

Also, it is important in my method that the hydrogen fluoride-borontrifluoride reaction system be operated so that there is not a net makeof butanes. In fact, I find it advantageous if there'be a consumption ofbutanes, and preferably there is consumed in the reaction at least about5 weight percent of butanes based on the C to C feed. The isobut'anecharged to my system can be relatively pure or mixed with othermaterials such as the various refinery hydrocarbons. Frequently, asfound in the refinery, the isobutane is in admixture with at leastnormal butane, and I can employ such mixtures. Of course, the isobutanecan be recycled from the reaction system effluent and usually at least aportion of any normal butane fed to the system is converted to isobutanewhich can be recycled and considered as part of the isobutanerequirement charged to the reaction zone. The amount of isobutane in thelight refinery streams could be increased as by contacts in anisomeriz-ation reaction stage with the catalyst passing to my HFBFconversion zone. The efiluent from this preliminary reaction is combinedwith my paraffin-rich feedstock and charged to the principal HFBFreaction system. The feed to the I-IF-BE, reaction system can alsoinclude materials such as propane, hydrogen or other light diluents.However, it is desirable to keep the concentrations of these materialslow since they are not as beneficial as isobutane and heat may have tobe supplied toany subsequent system to separate them from the reactionproduct. Also, these extraneous materials occupy space in the reactionsystem which could necessitate an increase in equipment size, and theymay in effect retard the desired reactions.

It may be that there are a number of reactions which are effected in mysecond stage system. For instance, while the parafiinic feed boilingpredominantly in the C to C range is undergoing isomerizati-on, theremay be a disproportionation of the small amount of C to C and Chydrocarbons. Moreover, there is evidence that relat-ively high octanegasoline components are produced possibly by polymerization and byalkylation. These and other reactions might be taking place in my systembut in any event I believe that the presence of the relatively largeamount of isobutane and the paraifinic materials in the overallhydrocarbon feed is necessary in obtaining the desired result which ismore than additive of that which would be expected from the conversionof the parafiins and isobutane in separate hydrogen fluoride-borontrifiuoride catalytic reaction systems.

The hydrocarbon feed to my essential HFBF catalytic process containslost octane normal parafiins boiling predominantly in the C to C range.Such materials are found in various petroleum refinery streams and canbe separated in more or less pure form or obtained in admixture withsimilar boiling isoparatfins and with materials such as olefins andaromatics. My hydrocarbon feedstocks contain at least about 15 percentof normal paratfin, preferably from 13 to 35 percent by weight. Thus thefeed while boiling predominantly in the C to C range may include smallamounts of n-pentane, n-hexane, nheptane or other C gasoline boilingrange normal parafiins either alone, mixed with each other or with theirisoparatfins or with similarly boiling olefins or aromatics.

As previously stated the feedstock for my hydrogen fluoride-borontrifluoride reaction system is a low octane par-aflinic concentrateeffluent of reforming systems employing platinum-alumina catalysts. Asan example most if not all of the aromatics of the reformate can beseparated as by adsorption, extractive distillation, or any otherprocedure desired. The paraffinic materials resulting are useful in myprocess when in a feed containing at least about 15 weight percent ofnormal parafiins and these stocks may also contain small amounts ofisoparaflins, olefins and aromatics. To obtain the desired selectiveparaflin-rich feed from the reformate, the aromatics can be adsorbed onsilica gel; or separated by solvent extraction through the use of asolvent selective for aromatics, e.g. phenol, or by any other desirableprocedure. A particularly useful method for accomplishing thisseparation is employed commercially and includes the use of aglycol-water extraction medium. As commercially licensed, one suchsystem is known as Udexing by regulation of conditions such as theglycol to water ratio, the extraction and solvent strippingtemperatures, and the character of the glycol, a Udex raffinate varyingin paraflinicity is obtained. The manner of controlling these factors isknown in the art and it sufiices to say that the preferred glycolmaterials are the diglycols such as diethylene and dipropylene glycolsand their mixtures.

Thus in the present invention I have devised a highly attractive methodfor obtaining higher octane fuels for spark ignition engines whichinvolves the use of separate reaction zones in which are employedcatalysts of different properties. In this method a straight rungasoline or naphtha boiling range hydrocarbon is contacted with aplatinum metal-alumina catalyst in the presence of free hydrogen underconditions which provide a substantial increase in the octane number ofthe petroleuin hydrocarbon material. A low octane parafiin-rich fractionboiling predominantly in the C to C range of the resulting reformate andisobutane are then contacted with the hydrogen fluoride and borontrifluoride catalyst according to a prescribed procedure to give aproduct boiling in the motor fuel range which is of substantiallyincreased octane quality.

The hydrocarbon feedstocks charged to the reaction system containing thepl-atinum-metal-alumina catalyst are primarily the straight runpetroleum fractions boiling in the gasoline and naphtha ranges, forinstance in the range from about 175 to 450 F., but somewhat higher orlower boiling constituents can be included if desired. Preferably, thefeedstock boils in the range of about 200 to 400 F. Although thehydrocarbons passing to the platinum metal-alumina catalyst reactionsystems are composed of predominantly straight run naphtha material,minor amounts of additional components can be included such as olefins,thermal and catalytioally cracked stocks, recycled reformate andfractions of these cracked and reformed materials. The reactionconditions observed or maintained in the platinum metal-alumina catalystsystem include those suggested for present commercial reformingoperations such as temperatures from about 750 to 1000 'F., preferablyabout 825 to 975 F., and pressures from about 50 to 1000 p.s.i.g.,preferably about 150 to 500 p.s.i.g. The free hydrogen supplied to thisreaction system usually is in the form of hydrogen-rich recycle gasesand generally provides about 2 to 20 moles of hydrogen per mole ofhydrocarbon feed; preferably this ratio is about 4 to 10:1. The spacevelocity usually lies in the range of about 0.5 to 10 WHSV (weight offeed per weight of catalyst per hour) preferably about 2 to 5 WHSV.

The platinum metal-alumina catalysts employed in the method of thisinvention include a number of compositions. Generally, the platinummetal is a minor amount of the catalyst, e.g. about 0.1 to 1.5 weightpercent of the final composition. Platinum is the most commonly employedmetal present in these reforming catalysts although other usefulplatinum metals include rhodium, palladium, iridium which, along withplatinum, are the face centered cubic crystallite types of the platinumfamily as distinct from the hexagonal types ruthenium and osmium whichappear to be of lesser value.

These catalysts can be made by a number of procedures but a particularlyeifective catalyst is one in which the alumina is obtained throughcalcination of an alumina hydrate containing at least about 65 weightpercent of trihydrate and about 5 to 35 weight percent of aluminamonohydrate and/or amorphous alumina forms, and advantageously having asurface area of about 350 to about 550 square meters per gram (BETmethod) when in the virgin state. The minor amount of platinum metal inthe catalyst is usually present in finely divided form and is notdetectable by X-ray diffraction techniques. Also, these catalysts areadvantageously prepared to afford about 0.10 to 0.5, preferably about0.15 to 0.3 cc./gram of their pore volume in pores of about to 1000Angstrom units in size. Application Serial No. 489,726, filed February21, 1955, describes the preparation of such catalysts. If desired, thecatalyst can contain minor amounts of additional materials, for instancepromoting components particularly those acidic in nature, such as silicaand fluoride. Such promoting components are usually less than 10 weightpercent of the final calcined catalyst.

The platinum metal-alumina catalyst can be employed in any type ofreaction system desired, for instance moving or fluidized bed,regenerative or non-regenerative, etc., but advantageously the catalystis disposed as a fixed bed. In the latter type of operation the size ofcommercial units is such that essentially adiabatic reaction systemsmust be employed and in View of this and the endothermic ature of thereforming operation the catalyst is placed in fixed beds in a pluralityof reactors, each of which is preceded by means for heating its charge.In fixed bed operations, the catalyst is in macrosize form, that is,particles generally at least about A in length and diameter andpreferably not exceeding about in diameter. Particularly 'when suchparticles are provided by extrusion, their length may be up to about 1"or more. If the platinum metal-alumina catalyst reforming system be ofthe regenerative type it can be arranged so that the catalyst of all ofthe reactors can be regenerated simultaneously or individually. Othervariations in the platinum metal catalyst reaction system can be madeaccording to the desires of the operator.

In the present invention, the essential feed to my hydrogenfluoride-boron trifl-uoride catalyst system is a paraffin-rich fractionboiling predominantly in the C to C range of the liquid reformate fromthe platinum metal catalyst operation, and as noted above, it includesat least 15 weight percent of normal parafiin constituents and usuallyless than about 10 weight percent of aromatics, preferably less thanabout 5 percent. This feedstock boils primarily in the C to C range,although lighter and heavier constituents can be included. Theparafiin-rich feed boiling predominantly in the C to C range can beobtained as a Udex raffinate and frequently the feed contains a minoramount of olefins. The character of this rafiinate can be controlled bythe boiling range of the reformate feed to the extractive distillation.As an example, if the reformate feed is of narrow boiling range, therafiinate will also be of close boiling range.

A typical Udex raftinate A is predominantly of C to C hydrocarbons andanalyzes as follows:

Gravity API, 60 F 67.4. AST M dist, -F.:

IBP 245. 50% 253.

Octane number (RON) 25.5 (neat), 60.1 (3 cc. TEL

added per gal).

Parafiins, vol. percent 95.5. 'Olefins, vol. percent 3.1. Naphthenes,vol. percent 0.0. Aromatics, vol. percent 1.4. Composition, vol.percent:

C l1 4 i-C 31 5 n-C 21.7 1-6 40.6 D-Cg In the hydrogen fluoride-borontrifluoride reaction system the conditions of treatment can vary widelydepending upon feed composition, octane number desired for the finalproduct, etc. I maintain the catalyst essentially in the liquid stateeven though when this is done it is quite likely that a portion of theboron trifluoride will also be present as vapor. Thus the pressuremaintained must be sufiicient to provide essentially liquid phasereaction conditions as determined by the vapor pressure of the hydrogenfluoride, boron trifiuoride, the react-ants and other materials such ashydrogen and the reaction products present. Generally, the borontrifiuoride partial pressure will be at least about 200 psi. andpreferably at least about 400 psi. in maintaining the liquid phasereaction. There seems to be little if any advantage in this partialpressure being above about 1500 psi. and at higher pressures propaneformation may be excessive. Thus, the total pressure will be at leastequal to the boron trifiuoride partial pressure and usually will not beabove about 2000 p.s.i.g. The reaction temperature and reaction contacttime are interdependent factors with a lesser time being required toprovide a given result as the temperature increases. The reactiontemperature will usually be in the range of about to 300 F, preferablyabout 75 to 200 F, with the time required ranging from about =1 minuteto hours, preferably about 5 minutes to 3 hours. Time longer than 5hours can be employed; however, no particular advantage would be derivedthereby which overcomes the obvious economic disadvantages. Although thecontact time and temperature employed can be selected as desired and caneven be dependent upon factors such as the type of reaction systememployed, I believe the following temperature-time relationships providethe best results but I do not intend to be limited by them.

TABLE I Temperature, F.: Contact time, minutes 100 30 to 180 100 to 200to 60 200 to 250 5 to 30 250+ 1 to 10 In general, I prefer to selectconditions which avoid production of substantial amounts of propane andlong contact times at high temperatures.

In the reaction zone enough hydrogen fluoride is added so that whencombined with the boron trifluoride a catalyst layer separate from thehydrocarbon can be obtained. Usually, this requires at least about onemole of hydrogen fluoride per mole of motor fuel range paraflmichydrocarbon feed. Preferably, this ratio is not greater than about 10 to-1 as larger amounts of hydrogen fluoride require excessive handlingfacilities. The amount of boron trifluoride added to the reaction systemhas been discussed above with reference to its partial pressure whichinsures adequate combination with the hydrogen fluoride. The hydrogenfluoride and boron trifluoride catalytic components can be addedseparately but preferably they are introduced into the reaction Zone inadmixture. The hydrogen fluoride-boron trifiuoride reaction system isusually conducted essentially in the absence of water to avoid having toincrease the amount of boron trifluoride, but frequently there are minoramounts of water present such as those derived through the use ofcommercially available hydrogen fluoride and boron trifluoride.

The hydrocarbon product and the hydrogen fluorideboron trifluoridecatalyst layers can be separated in any manner desired. When agitationof the reaction mixture is stopped it will separate into two phases inthe reactor or in any other vessel into which it is transferred as in acontinuous, semi-continuous or batch operation. These phases can beseparated by simple decantation. The reaction mixture could be allowedto separate into a lower layer of catalyst containing aromatics whichcan be recycled to the reaction system in whole or in part. Usually, Ikeep the aromatic content of the predominantly C to C hydrocarbon feedat less than about 10 Weight percent, preferably less than about 5percent. In designating amounts of aromatics, I refer to the valuesobtained by the Fluorescence Indicator method commonly known as the ETA.method involving chromatography on silica gel. The upper hydrocarbonlayer formed in my system could be freed from catalyst by distillationand/ or washing with water or passed through a column of basic ionexchange resin or other solid adsorbent such as charcoal, potassiumsulfate, sodium sulfate, etc. Aromatics appearing in the catalyst layercould be separated as by distillation of the catalyst, and the aromaticsmight then be combined with the hydrocarbons of the upper layer toprovide a higher octane product. However, the recovered aromatics may beheavier than gasoline. Small traces of fluoride remaining in thehydrocarbon material can be removed as by passage over aluminum oralumina at 200 to 400 F. Various drying procedures could be employed toseparate water from the hydrocarbon materials and such materials couldbe stabilized, for instance by the removal of C s and lighterconstituents.

In the drawing I have illustrated a simplified flow sheet of oneoperation conducted in accordance with my method.

In this system straight run naphtha is charged by way of line 1 toheater 2 and then through line 3 to the top of an initial reactor 4which contains a fixed bed of platinum-alumina catalyst. The efiluentfrom reactor 4 is passed by way of line 5 to heater 6 and then throughline 7 to the top of a second reactor 8 containing a fixed bed ofplatinum-alumina catalyst. The platinum-alumina catalyst reactionsection 'is of the adiabatic type and more than two reactors can beprovided if desired and in fact usually at least three catalyst beds inseparate reactors will be employed with each reactor having associatedtherewith a 'feed preheater. A third heater 9 and third reactor 10*containing a fixed bed of platinum-alumina catalyst are shown in thedrawing.

The reformate from the bottom of reactor 10 is passed by way of line 11to flash drum 12' which separates C s and lighter materials which arepassed through line 13 to separator 14. The separator provides forremoval of 7? C to C hydrocarbon constituents through line 15 andhydrogen and methane are recycled by way of line 16 to line 1. Excesshydrogen and methane can be removed from line 16 by way of line 17.

The liquid reformate from flash drum 12 is passed through line 18 to anintermediate portion of distillation column 19 and a light gasoline istaken overhead through line 20. The bottoms fraction from column 19 iscarried by line 21 to an intermediate portion of distillation column 22and heavy gasoline is removed as bottoms from this column through line23. The overhead from column 22 is passed by way of line 24 to storagetank 25. Liquid hydrocarbon is withdrawn from the storage tank throughline 26 and passed to an intermediate portion of extractor 27. Enteringnear the top of extractor 2'7 through line 28 is a glycol-waterextractive medium. The raffinate produced in the extraction operation istaken overhead by line 29 and transported to storage tank 2%. Theextract passes by way of line 30 to an intermediate portion of stripper31. The stripped extractive medium then returns to extractor 27 throughline 28. The overhead from stripper 31 is returned by line 32 to thelower portion of extractor 27.

A side stream from stripper 31 is charged to distillation column '34 anda toluene-containing overhead is removed by line 35. The bottoms fromcolumn 34 pass by way of line 36 to an intermediate portion ofdistillation column .37 from which xylenes are removed as overhead byline 38. The bottoms fraction from column 37 contains polymers and isremoved by way of line 39.

The raffinate from storage tank 29a is charged through line 41 toreactor 40 after the addition of isobutane by way of line 41a. Thehydrogen fluoride-boron trifiuoride catalyst mixture enters reactor 40through line 42. The reaction efiluent is carried to separator 43 wherea hydrocarbon phase and a catalyst phase are formed. The catalyst phasecan be recycled to the reactor through lines 44 and 42 while thehydrocarbon phase is passed to the intermediate portion of fractionator45. C minus overhead -from the fractionator goes to separator 46. Inthis separator, the C hydrocarbons are obtained and then recycled by wayof lines 47 and 41 to reactor 40. C and lighter materials are removed byline 48 from separator 46. A gasoline fraction is taken as a side streamfrom fractionator 45 by way of line 49 while heavier hydrocarbons arewithdrawn from the fractionator in bottoms line 50.

Although the drawing provides an illustration of a typical process I canemploy, it is not to be considered limiting; for instance, theparafiinic fraction of catalytic reformate can be charged to thehydrogen fluoride-boron trifiuoride reaction system in admixture withsmall amounts of extraneous relatively close cut hydrocarbons such asn-pentane, n-hexane, n-heptane or mixtures of these normal paraflinswith their isomers. As an example, the catalytic reformat-e might beflashed to remove C and lighter hydrocarbons and a C to C fractionseparated by distillation. The resulting C reformate can be treated toobtain a paraiiind'ich fraction of pre-v dominantly C3 to C which isthen charged to the hydrogen fluoride-boron trifiuoride reaction system.The isobutane is provided by recycle from the reaction zone and inaddition extraneous normal and isobutanes can be added to the reactionzone as desired. The motor fuel boiling range products would thencomprise essentially the gasoline obtained from the paraflin-richportion of the reformate and isopentane produced in the hydrogenfluoride-boron trifluoride system due to the charging of n-pentane inthe C to C fraction of the retormate. This reformate fraction would alsocontain isopentanes which could be isomerized to greater degrees ofbranching or merely carried through the hydrogen fiuoride-boron trifluoride reaction system. These isopentanes would also appear in themotor fuel boiling range product.

8 Example I A straight run naphtha is obtained by distillation fromcrude oil, and the naphtha typically has an ASTM distillation boilingrange of about 209 to 381 F., a RON (neat) of about 47.2, and a gravityAPI 60 F. of about 56.7. This naphtha is fed to a reforming unitcontaining three essentially adiabatic reactors each having a fixed bedof a platinum-alumina reforming catalyst. This system is equipped withmeans for heating the charge to each reactor and the heaters andreactors are arranged for serial flow. The catalyst employed is aplatinum-alumina reforming catalyst containing about 0.6 weight percentplatinum, and manufactured in accordance with application Serial No.489,726, listed above. The inlet temperatures of the feed to each of thethree catalyst beds are 940 F while the pressure is about 500 p.s.i.g.Free hydrogen is supplied to the feed passing to the heater before thefirst reactor and the hydrogen is obtained by recycle from the thirdreactor efiluent stream. The molar ratio of hydrogen-rich recycle gas(72.7% H to hydrocarbon feed is approximately 5.5 to 1, while theoverall space velocity is about 2.34 WHSV. The efiluent from the lastreactor is conveyed to a flash drum operating at 500 p.s.i.g. and isthen treated or depropanized to remove C and lighter hydrocarbons bydistiallation. Inspection on the resulting reformate is as follows:

Gravity API, 60 F 53. ASTM distillation, F

IBP 112.

EP 397. Octane number (RON) 84.9 (neat), 95.3 (3 cc. TEL

added/ gal.) Percent aromatics 51.2 (by F.I.A.). Percent olefins 0 (byF.I.A.).

To facilitate an understanding of this example the extractivedistillation operation will be described with reference to the drawing.Thus, 6.71 parts by volume of the 112 to 397 F. boiling range reformateare passed at a temperautre of 222 F. to an intermediate portion ofdistillation column 19. The column top temperature is 215 F. and thecolumn bottom temperature is 336 F. In column 19, 2.54 parts by volumeof light gaso line are separated as overhead and this gasoline has agravity API 60 F. of 71.1 and a boiling range of about 108 to 216 F.3.17 parts by volume of the bottoms from column 19 are charged at 316 F.to an intermediate portion of distillation column 22. This column has atop temperature of 279 F. and a bottom temperature of 348 F. Theoverhead from column 22 is 2.24 parts by volume and the bottoms fractionis 0.93 part by volume of a heavier gasoline fraction. The overhead fromcolumn 22 has a gravity API 60 F. of about 46.2 and a boiling range ofabout 250 to 284 F.

The feed to the intermediate portion of extractor 27 is 1.622 parts byvolume of the column 22 overhead. The tower top and bottom temperaturesof the extractor are 280 F. and there results 0.838 part by volume ofraffinate overhead from the extractor. The bottoms from the extractor ispassed to the intermediate portion of stripper 31 which has a toptemperature of 231 F. and a bottom temperature of 297 F. 8.16 parts byvolume of extractive medium are separated as bottoms from stripper 31and passed to the top of extractor 27. This extractive medium containsabout 17% by volume of dipropylene glycol, 75.5% by volume of diethyleneglycol and 7.5% by volume of water.

0.78 part by volume of a side stream from stripper 31 are charged at 292F. to column 34. The top temperature of this column is 232 F. and thebottom temperature is 299 F. The overhead is 0.186 part by volume of afraction consisting essentially of toluene. 0.598 part by volume arewithdrawn as bottoms from column 34 and passed at 291 F. to column 37which has a top temperature of 285 F. and a bottom temperature of 305 F.The overhead from column 37 is 0.597 part by volume of a fractionconsisting essentially of Xylenes and the botl conducted through a DryIce cooling trap, safety trap, water scrubber, gas sampler and wet testmeter. The hydrocarbon layer is separated from the ice water and theformer is washed three times with separate 500 cc.

toms is 0.001 part by volume of polymer. portions of water. The washedhydrocarbon is dried by A 1750 ml. stainless steel Magne-dash bombhaving contact with potassium carbonate. The products obtapered Walls togive maximum thickness in the bottom tained are 191 grams of liquidhydrocarbon, 237 grams half of the bomb is evacuated with a vacuum pump.of condensible gas and 3.74 liters (STP) of dry gas Cold liquid hydrogenfluoride (124.6 grams is drawn into (mostly air). The condensible gasand liquid are then the bottom of the bomb through a copper tube. 180-combined and distilled through a 12" glass helices vacuum butane (219grams) 1S pressured into the bomb from a jacketed distillation column toseparate 205.5 grams of pressure cylinder. 3.92 moles of borontrifluoride are C -C wet gas, 175 grams of initial to 435 F. overheadcharged into the bomb by pressuring from a 2-liter cylingasoline, and 31grams of still residue boiling above der. The amount of borontrifiuoride introduced is esti- 435 F. The yield of gasoline whencorrected for the matfid y interpolation from the a of K p k andapproximate 9% handling and mechanical losses is 100.1 Luborsky, 76 5865The bomb P volume per-cent based on the rafiinate feed and inspectingsure is 530 p.s.i.g. and the temperature is 80 F. The as f ll contentsor the bomb are stirred while pressuring in from Gravity APL 5 R a blowcase 310 cc. (226 grams) of the overhead from Octane number (RON) 852(neat). extractor 27. Thus, the isobutane to rafiinate Weight ratioPercent aromatics 0.0 (by FlA.) is 0.97 to 1. The charging of theoverhead is over a Percent olefins 147 (b 5 a y period of one minute andthe temperature rises to 90 Bromine number 135 F. while the pressuregoes to 575 p.s.i.=g. Inspection of the RVR 12 6'lbs raffinate feedwhich contains at least about 15% n-paraf- Th t d M g T I t fins (waterwashed and dried extractor overhead) is: 3 Congo 6 We propane 1S v0 1Percen 0 while the corrected yield of hydrocarbon boiling above GraVtYAm 9 435 F. is 11.2 volume percent. The total butanes re- ASTMdlstlnalon, 4 covered are less than those charged to the hydrogen IBP 2fluoride-boron trifluoride reaction zone by 7 volume per- 50% cent basedon the rafiinate feed and the recovered butanes 90% contain 90 molepercent of isobutane. Thus about 7 EP volume percent of butanes areconsumed in the reaction Octane number (RON) 32.0 (neat), 64.7 (3 cc.basgd upon the raffinate feed TELaddw/gam- The yield-octane advantageobtained by charging the substantial amount of isobutane to my operationcan be Percent aromatics (by readily seen by comparing several runs madein which Percent Olefins 23 (by the amount and nature of the lighterhydrocarbon portion Stirring of the contents of the bomb is continuedfor of the feed are varied. In these runs, the feed was the anadditional 51 minutes and the temperature drops to U'dex rairinate ofExample I; and, except for run 5, the 85 F. and the pressure goes to 450p.s.i. g. While stir- HFBF reaction system was conducted essentially asring, the contents of the bomb are discharged into a miX- described inExample I under the conditions noted in ture of ice and water throughthe bottom take-off valve. the following table. The procedure andconditions of The discharging requires about 9 minutes. Gases are run 5are also given in this table, that is, run 5 was pro- TABLE Run 1 2 3Ex. I 4 5 9 6 7 8 Temp, F. Initial/Final 01' Initial/Maximum/Fin 90/8079/76 160/169/155 90/85 77/70 79/71 84/80 85/80 Pressure, p.s.i.g.,Initial/Final or In Maximum/Final 585/405 590/440 760/770/725 575/4501400/1420/1390 500/480 520/435 580/450 610/475 gondtact Time, min 62 60.5 61 60 59 60 6 60 60 Udex Ralfinate:

g.. 436 343 311 226 197 o 54. 6 237 229 230 cc 600 469 426 310 270 75325 315 315 Isobutane:

g 106 96 219 573 321. 5 b 278 199 230 cc 176 159 348 954 582 475 355 410Catalyst HF, g 122. 4 127 124. 6 182 110. 9 125. 1 115 108 13m, mo1cs 3.74 3. 76 3. 92 5. 62 3. 34 3. 92 3. 88 3. 88 Products:

Liquid Hydrocarbon, g 346 284 158 191 148 15 174 209 172 CondensiblcGas, g 59 148 286.5 237 583.5 331 305 185 234 Dry Gas, liters STP 2 922. 77 4.08 3. 74 4. 72 5 5.13 2.1 1. 3 Recovery, Wt., Percent 76 86 9791 94 91 94 68 Total 115.0 105.3 106.4 113.4 Butsnes Consumed 0 0 7Percent Isobutane in C4 Fraction 93 91 36 90 Gasoline:

o.N. (R.M. neat) 75. 2 81. 2 82. 8 85. 2 FIAAromatics 0. 0 0. 0 0. 0 0.0 Olefins--. .4 18.9 15. 8 14. 7 R.V.P 10. 75 12. 6

Gallons per gallons ralfinate in feed. n-Butane.

9 Isobutane HF and B F3 were all in bomb and Udex Raflinate was chargedat the rate 0f1% (ac/min. during 1 hour.

d Based upon combined materials of Runs 7 and 8.

e The paraflins of the Udex rafiinate are about 49.9 weight percent CBand about 49.4 weight percent C9, sec Example I for the othercharacteristics of the ratfinate. Raflinate A described above could beused in the examples.

1 l cedurally similar to Example *1 except for the charging of the bomb.

The data of this table show that in run 1 conducted in the absence ofisobutane the gasoline product had an octane number of 75.2 and theyield was only 56.8 percent whereas in Example I, this yield was 100.1percent at 85.2 octane number. Runs 7 and 8 closely check EX- ample I inthese respects, and in these systems the isobutane to ralfinate Weightratios were in the range from about 0.87 to 1/ 1. In runs 2 and 3 wherethis ratio was only around 0.3/1 the gasoline yield was considerablyreduced and there was a butanes make instead of a consumption as inExample I and runs 7 and 8. In run 6 where n-butane replaced theisobutane, the octane of the product was good but the yield of gasolinewas low and there was a net production of butanes.

In another operation 70.6 grams of liquid hydrogen fluoride and 251grams of isobutane are placed in the Magne-dash bomb of Example I. 2.3moles of boron trifluoride are charged into the bomb by pressuring froma 2-liter cylinder, and this amount is estimated according to the methodpreviously noted. The bomb pressure is 430 p.s.i.g. and the temperatureis 63 F. While stirring its contents, the bomb is heated to 250 F. overa period of 1 hour and the pressure rises to 1615 lbs. This temperatureis held for 1 hour and the products are discharged into ice water. Theresulting separated hydrocarbon product analyzes as follows:

Component Weight percent C s 0.4 Propane 1.2 N-butane 8.7

Isobutane 88.6

Isopentane 0.8 N-pentane 0.1

It is seen that even under these severe reaction conditions littleconversion of the isobutane is accomplished.

The advantageous yield-octane number relationship resulting from mymethod, for instance in Example I, is far better than would have beenexpected from the results received when treating the Udex raftinate (seerun 1 of the foregoing table) and the isobutane with the hydrogenfiuoride-boron trifluoride in separate reaction systems. It is thereforeapparent that my use of the paramnic hydrocarbons boiling predominantlyin the C to C range in conjunction with the substantial amount ofisobutane under conditions where there is not a net make of butanes isresponsible for my highly improved results.

I claim:

1. In a method of converting a straight run hydrocarbon fraction boilingin the motor fuel range, the steps comprising contacting saidhydrocarbon fraction with a platinum metal-alumina catalyst in thepresence of free hydrogen at a temperature of about 750 to 1000 F. and apressure of about 50 to 1000 p.s.i.g. to provide a product boiling inthe motor fuel range of increased octane value, separating from thisproduct paraffinic hydrocarbons consisting essentially of parafiinichydrocarbons boiling predominantly in the C to C range, said paraflinichydrocarbons containing at least about 15 weight percent of normalparafiin and having less than about 10 weight percent aromatics,contacting in the liquid phase isobutane and the separated paraffinichydrocarbons with a catalyst consisting essentially of hydrogen fluorideand boron trifluoride at a temperature of about to 300 F. and at a borontrifiuoride partial pressure of at least about 200 p.s.i. with therebeing a net consumption of butanes of at least about 5 weight percentbased upon platinum-alumina catalyst in the presence of free hydrogen ata temperature of about 825 to 975 F. and a pressure of about to 500p.s.i.g. to provide a product boiling in the motor fuel range ofincreased octane value, separating from this product paraffinichydrocarbons consisting essentially of paraffinic hydrocarbons boilingpredominantly in the C to C9 range and having less than about 10 percentaromatics, said parafiinic hydrocarbons containing about 15 to 35 weightpercent of normal paraffin, contacting in the liquid phase isobutane andthe separated parallinic hydrocarbons with a catalyst consistingessentially of hydrogen fluoride and boron trifluoride at a temperatureof about 75 to 200 F. and at a boron trifluoride partial pressure of atleast about 4-00 p.s.i. with there being a net consumption of butanes ofat least about 5 weight percent based upon the said parafiinichydrocarbon, said contacted isobutane being about 75 to 300 weightpercent of said paraflinic hydrocarbon, and separating a hydrocarbonboiling in the motor fuel range.

3. In a method of converting a straight run hydrocarbon fraction boilingin the motor fuel range, the steps comprising contacting saidhydrocarbon fraction with a platinum metal-alumina catalyst in thepresence of free hydrogen at a temperature of about 750 to 1000 F. and apressure of about 50 to 1000 p.s.i.g. to provide a product boiling inthe motor fuel range of increased octane value, separating by means of aglycol-water extraction medium from this product parafiinic hydrocarbonsconsisting essentially of parafiinic hydrocarbons boiling predominantlyin the C to C range, said parafiinic hydrocarbons containing at leastabout 15 weight percent of normal paraflin and having less than about 10weight percent aromatics, contacting in the liquid phase isobutane andthe separated parafiinic hydrocarbons with a catalyst consistingessentially of hydrogen fluoride and boron trifiuoride at a temperatureof about 0 to 300 F. and at a boron trifluoride partial pressure of atleast about 200 p.s.i. with there being a net consumption of butanes ofat least about 5 weight percent based upon the said parafiinichydrocarbons, said contacted isobutane being about 50 to 600 Weightpercent of said paraflinic hydrocarbon, and separating a hydrocarbonboiling in the motor fuel range.

4. In a method of converting a straight run hydrocarbon fraction boilingin the motor fuel range, the steps comprising contacting saidhydrocarbon fraction with a platinum-alumina catalyst in the presence offree hydrogen at a temperature of about 825 to 975 F. and a pressure ofabout 150 to 500 p.s.i.g. to provide a product boiling in the motor fuelrange of increased octane value, separating by means of a glycol-waterextraction medium from this product paraffinic hydrocarbons consistingessentially of paralfinic hydrocarbons boiling predominantly in the C toC range and having less than about 10 percent aromatics, said paraffinichydrocarbons containing about 15 to 35 weight percent of normalparafiin, contacting in the liquid phase isobutane and the separatedparaffinic hydrocarbons with a catalyst consisting essentially ofhydrogen fluoride and boron trifluoride at a temperature of about 75 to200 F. and at a boron trifluoride partial pressure of at least about 400p.s.i.g. with there being a net consumption of butanes of at least about5 weight percent based upon the said paratlinic hydrocarbon, saidcontacted isobutane being about 75 to 300 weight percent of saidparafiinic hydrocarbon, and separating a hydrocarbon boiling in themotor fuel range.

References Cited in the file of this patent UNITED STATES PATENTS2,583,740 Kemp Jan. 29, 1952 2,740,751 Haensel et al Apr. 3, 19562,781,298 Haensel et al. Feb. 12, 1957 2,877,173 Thorne et al Mar. 10,1959 2,880,164 Viland Mar. 31, 1959 2,917,449 Christensen et al Dec. 15,1959 2,938,853 Amer et al. May 31, 1960

1. IN A METHOD OF CONVERTING A STRAIGHT RUN HYDROCARBON FRACTION BOILINGIN THE MOTOR FUEL RANGE, THE STEPS COMPRISING CONTACTING SAIDHYDROCARBON FRACTION WITH A PLATINUM METAL-ALUMINA CATALYST IN THEPRESENCE OF FREE HYDROGEN AT A TEMPERATURE OF ABOUT 750 TO 100*F. AND APRESSURE OF ABOUT 50 TO 1000 P.S.I.G. TO PROVIDE A PRODUCT BOILING INTHE MOTOR FUEL RANGE OF INCREASED OCTANE VALUE, SEPARATING FROM THISPRODUCT PARAFFINIC HYDROCARBONS CONSISTING ESSENTIALLY OF PARAFFINICHYDROCARBONS BOILING PREDOMINANTLY IN THE C8 TO C9 RANGE, SADIPARAFFINIC HYDROCARBONS CONTAINING AT LEAST ABOUT 15 WEIGHT PERCENT OFNORMAL PARAFFIN AND HAVING LESS THAN ABOUT 10 WEIGHT PERCENT AROMATICS,CONTACTING IN THE LIQUID PHASE ISOBUTANE AND THE SEPARATED PARAFFNICHYDROCARBONS WITH A